Nielsen (crater)
Nielsen is a lunar impact crater on the Oceanus Procellarum. It is located north-east of Montes Agricola on the western hemisphere of the Moon. To the east-southeast is the crater Wollaston.
Nielsen is a bowl-shaped formation that lies astride a small ridge that runs north-northwestwards towards the Mons Rümker. The latter is an unusual raised formation of lunar domes.
The crater is named jointly after the Danish astronomer Axel Nielsen and the Danish–American physicist Harald Herborg Nielsen.